1. Field of the Invention
Leaf spring arrangements for upholstered furniture seating has advantages in strength, comfort and durability when compared to traditional coil or sinuous wire springs. Greater stability and control in the movement of the springs under load provide added durability for fabrics and upholstery. Because of the strength of the leaf springs, in some uses, additional flexing segments provide improved comfort and reduced metal fatigue thereby increasing both comfort and durability. Supporting a leaf spring array from a coil spring array maximizes comfort and durability by isolating fatigue and support and comfort related functions.
2. Description of Related Art
U.S. Pat. Nos. 2,788,844 and 3,156,460 show basic leaf spring structures used to support a seat deck in upholstered furniture. U.S. Pat. No. 5,269,497 shows a more recent improvement which includes a single V arch near the front and/or rear frame member of the leaf. The basic spring has the drawbacks of metal fatigue when the leaves are of small, very flexible dimensions when sized for greater flexibility and certain comfort parameters. Because of the stiffness of metal leaf springs, the area of the springs in the three patents mentioned is a relatively small percentage of the area of the seat deck, therefore the load is spread over a large number of small leaves. The single V-arch spring remedies the fatigue and durability issues to an extent, but still has a relatively small support area and has additional limitations in control of flexing on an overall seat spring assembly These patents are incorporated by reference as if fully set forth herein. Other patents have taught the use of coil spring supported bars, rods, or other seat decks, but not coil springs used in combination with leaf springs. The invention optimizes durability and comfort and provides improved utility in that a greater number of combinations of spring performance are available.